The free world is the new continent in cyberspace that we have built so we can live here in freedom. It's impossible to live in freedom in the old world of cyberspace, where every program has its feudal lord that bullies and mistreats the users. So, to live in freedom we have to build a new continent. Because this is a virtual continent, it has room for everyone, and there are no immigration restrictions. - Richard Stallman -

A tag editor (or tagger) is an application which allows users to edit metadata of multimedia files. Metadata is the data about the audio data. It lets information about the audio file such as the title, artist, conductor, album, track length, lyrics, embedded images, and other information be stored in the audio file itself.

The most common form of audio tag is ID3, of which there are two unrelated types (ID3v1 and ID3v2). There are also other types of audio tags, including Vorbis Comments (found in Ogg and FLAC audio files), and APE tags. Tag editors are not just confined to audio files. Taggers for graphic formats (such as JPEG and TIFF) are also available.

Tag editors are frequently used to correct and organise multimedia files and they support popular digital audio formats. They can rename files based on the tag information, replace words in tags and filenames, create playlists, and import/export tag information. An important feature we look for is the ability to make online database lookups, saving valuable time in collating tags and cover art for your music collection.

To provide an insight into the quality of software that is available, we have compiled a list of 5 proficient music tag editors. Hopefully, there will be something of interest here for anyone who wants to keep their music collection organised.
Now, let's explore the 5 music tag editors at hand. For each title we have compiled its own portal page, a full description with an in-depth analysis of its features, screenshots, together with links to relevant resources and reviews.Kid3.Kid3 is an application to edit the ID3v1 and ID3v2 tags in MP3 files in an efficient way. These tags can be edited by most MP3 players, but not in a very comfortable way. Moreover the tags in Ogg/Vorbis, FLAC, MPC, MP4/AAC, MP2, Speex, TrueAudio and WavPack files are supported too.
Where most other programs can edit either ID3v1 or ID3v2 tag s, Kid3 has full control over both versions, can convert tags between the two formats and has access to all ID3v2 tags.
Please note, Kid3 does not grab, encode nor play MP3 files.
Features include:

MusicBrainz Picard ("Picard") is a cross-platform MusicBrainz tag editor written in Python.Picard is intended to be the next generation of tagger for the MusicBrainz application, with a focus on album-oriented (as opposed to track-based) tagging and cross platform compatibility.
Features include:

Supports the following formats:

MP3, TTA (ID3)

Ogg Vorbis, FLAC, Speex (Vorbis comment)

Musepack, WavPack, OptimFROG, Monkey's Audio (APEv2 tag)

AAC, ALAC (MP4)

The True Audio

Windows Media Audio

WAV

Automatic identification of audio files through the MusicDNS service using the Open Fingerprint Architecture acoustic fingerprinting technology

Pinky-Tagger is a mass tagger for Linux which supports the MusicBrainz (PUID & TRM) service to find the correct tag information for your files automatically.
With Pinky-Tagger, you can manage your files, download cover, tag via an integrated expression scanner, tag via the MusicBrainz information or even listen to your files (external player support).
Features include:

View, edit, write tags of MP3, FLAC, Ogg and Monkey's Audio files

Support OFA/PUID fingerprint generation

Supports the MusicBrainz (version 3) service

Download cover and save them to disk

Download album information with or without automatic preselection of album suggestions

Tag complete albums

Browse files with internal file- and directory browser

Recursion directory mode for tagging

Read file information like (bitrate, time and so on) and displays them

Rename files via expression scanner from tag information

Tag files via expression scanner from file name

Control your favorite external player (play, append to playlist, pause and so on)

Tag files where you do not have any information (empty tag and unplausible filename for example)

Decode with the fast libffmpeg (internal) or with "lame" (external) for fingerprint generation

Powerful album tagger with automatic track assignment functionality

Fully Drag & Drop compatible

Offline mode

Fast track browsing with internal MusicBrainz & MusicDNS cache

Mark directories as tagged, files missing or untagged for better album management

EasyTAG is a utility for viewing, editing and writing the ID3 tags of different audio files, using an intuitive graphical interface.
The interface displays basic file informations taken from the file header, such as bitrate or duration. With the interface, you can edit common tag fields including: title, artist, album, year, track number, genre and comment which were available into ID3v1.1 and ID3v2.3 tag. Users can also edit special ID3v2.3 fields like: disc album, composer, original artist/performer, copyright, URL, encoder name and attached pictures.
Features include: